Circuitry for electrical redundancy in bonded structures

ABSTRACT

A bonded structure is disclosed. The bonded structure can include a first element that has a first plurality of contact pads. The first plurality of contact pads includes a first contact pad and a second redundant contact pad. The bonded structure can also include a second element directly bonded to the first element without an intervening adhesive. The second element has a second plurality of contact pads. The second plurality of contact pads includes a third contact pad and a fourth redundant contact pad. The first contact pad is configured to connect to the third contact pad. The second contact pad is configured to connect to the fourth contact pad. The bonded structure can include circuitry that has a first state in which an electrical signal is transferred to the first contact pad and a second state in which the electrical signal is transferred to the second contact pad.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to U.S. Provisional Patent ApplicationNo. 62/953,084, filed Dec. 23, 2019, the entire contents of which arehereby incorporated by reference herein in their entirety and for allpurposes.

BACKGROUND Field

The field relates to circuitry for electrical redundancy in bondedstructures.

Description of the Related Art

Multiple semiconductor elements (such as integrated device dies) may bestacked on top of one another in various applications, such as highbandwidth memory (HBM) devices or other devices that utilize verticalintegration. The stacked elements can electrically communicate with oneanother through arrays of contact pads. It can be important to ensurethat the electrical connections between contact pads on two stackedelements are reliable.

BRIEF DESCRIPTION OF THE DRAWINGS

Specific implementations will now be described with reference to thefollowing drawings, which are provided by way of example, and notlimitation.

FIG. 1A is a schematic top plan view of a bonded structure showinglocations of voids.

FIG. 1B is a schematic cross sectional view of the bonded structure ofFIG. 1A.

FIG. 1C is a schematic cross sectional view of a bonded structureaccording to an embodiment.

FIG. 2A illustrates switching circuitry comprising a bi-directionalcircuit according to an embodiment.

FIG. 2B illustrates switching circuitry comprising a bi-directionalcircuit according to another embodiment.

FIG. 2C illustrates switching circuitry comprising a demultiplexer(DEMUX) according to an embodiment.

FIG. 2D illustrates switching circuitry comprising a multiplexer (MUX)according to an embodiment.

FIG. 3 illustrates switching circuitry comprising an AND gate accordingto an embodiment.

FIG. 4 illustrates switching circuitry comprising a plurality ofmultiplexers (MUX) according to an embodiment.

DETAILED DESCRIPTION

Two or more semiconductor elements (such as integrated device dies) maybe stacked on or bonded to one another to form a bonded structure.Conductive contact pads of one element may be electrically connected tocorresponding conductive contact pads of another element. Any suitablenumber of elements can be stacked in the bonded structure. In someembodiments, the elements are directly bonded to one another without anadhesive. In other embodiments, the elements may be bonded with aconductive adhesive, such as solder, etc.

In various embodiments, a dielectric field region of a first element(e.g., a first semiconductor device die with active circuitry) can bedirectly bonded (e.g., using dielectric-to-dielectric bondingtechniques) to a corresponding dielectric field region of a secondelement (e.g., a second semiconductor device die with active circuitry)without an adhesive. For example, dielectric-to-dielectric bonds may beformed without an adhesive using the direct bonding techniques disclosedat least in U.S. Pat. Nos. 9,391,143 and 10,434,749, the entire contentsof each of which are incorporated by reference herein in their entiretyand for all purposes. Dielectrics that can be treated and activated fordirect bonding include, for example, inorganic dielectrics, particularlythose including silicon, such as silicon oxide (SiO), silicon nitride(SiN), silicon carbide (SiC), silicon oxynitride (SiON), siliconoxycarbide (SiOC), silicon carbonitride (SiCN), etc.

In various embodiments, hybrid direct bonds can be formed without anintervening adhesive. For example, dielectric bonding surfaces can bepolished to a high degree of smoothness. The bonding surfaces can becleaned and exposed to a plasma and/or etchants to activate thesurfaces. In some embodiments, the surfaces can be terminated with aspecies after activation or during activation (e.g., during the plasmaand/or etch processes). Without being limited by theory, in someembodiments, the activation process can be performed to break chemicalbonds at the bonding surface, and the termination process can provideadditional chemical species at the bonding surface that improves thebonding energy during direct bonding. In some embodiments, theactivation and termination are provided in the same step, e.g., a plasmaor wet etchant to activate and terminate the surfaces. In otherembodiments, the bonding surface can be terminated in a separatetreatment to provide the additional species for direct bonding. Invarious embodiments, the terminating species can comprise nitrogen.Further, in some embodiments, the bonding surfaces can be exposed tofluorine. For example, there may be one or multiple fluorine peaks nearlayer and/or bonding interfaces. Thus, in the directly bondedstructures, the bonding interface between two dielectric materials cancomprise a very smooth interface with higher nitrogen content and/orfluorine peaks at the bonding interface. Additional examples ofactivation and/or termination treatments may be found throughout U.S.Pat. Nos. 9,564,414; 9,391,143; and 10,434,749, the entire contents ofeach of which are incorporated by reference herein in their entirety andfor all purposes.

In various embodiments, conductive contact pads of the first element canbe directly bonded to corresponding conductive contact pads of thesecond element. For example, a hybrid bonding technique can be used toprovide conductor-to-conductor direct bonds along a bond interface thatincludes covalently direct bonded dielectric-to-dielectric surfaces,prepared as described above. In various embodiments, theconductor-to-conductor (e.g., contact pad to contact pad) direct bondsand the dielectric-to-dielectric bonds can be formed using the directhybrid bonding techniques disclosed at least in U.S. Pat. Nos. 9,716,033and 9,852,988, the entire contents of each of which are incorporated byreference herein in their entirety and for all purposes.

For example, dielectric bonding surfaces can be prepared and directlybonded to one another without an intervening adhesive. Conductivecontact pads (which may be surrounded by nonconductive dielectric fieldregions) may also directly bond to one another without an interveningadhesive. In some embodiments, the respective contact pads can berecessed below the dielectric field regions, for example, recessed byless than 20 nm, less than 15 nm, or less than 10 nm, for example,recessed in a range of 2 nm to 20 nm, or in a range of 4 nm to 10 nm.The dielectric field regions can be initially directly bonded to oneanother without an adhesive and without external pressure at roomtemperature in some embodiments and, subsequently, the bonded structurecan be annealed. Upon annealing, the contact pads can expand and contactone another to form a metal-to-metal direct bond. Beneficially, the useof the hybrid bonding techniques known by the trade name Direct BondInterconnect, or DBI®, can enable high density of pads connected acrossthe direct bond interface (e.g., small or fine pitches for regulararrays) and/or high density of pads connected across the direct bondinterface (e.g., small or fine pitches for regular arrays). In someembodiments, the pitch of the bonding pads may be less 40 microns orless than 10 microns or even less than 2 microns. For some applicationsthe ratio of the pitch of the bonding pads to one of the dimensions ofthe bonding pad is less than 5, or less than 3 and sometimes desirablyless than 2. In various embodiments, the contact pads can comprisecopper, although other metals may be suitable.

In various embodiments, the contact pads can be formed in respectivefirst and second arrays of pads on the first and second elements. If anydebris or surface contaminant is present at the surface of the first orsecond elements, voids may be created at the bond interface, or debrismay intervene between opposing contact pads. In addition, reactantbyproducts generated during bonding and annealing, e.g. hydrogen andwater vapor, may also form voids at the bond interface. These voids mayeffectively inhibit the joining of particular contact pads in thevicinity, creating openings or other failures in the bond. For example,any void larger than the pad diameter (or pitch) can potentially createan opening and direct bond failure.

FIG. 1A is a schematic top plan view of a bonded structure 1 showinglocations of voids 10. FIG. 1B is a schematic cross sectional view ofthe bonded structure 1. The bonded structure 1 has voids 10 between afirst element 12 and a second element 14. The voids 10 can intervenebetween opposing contact pads 16, 18. The voids 10 can cause faultyinterconnects.

FIG. 1C is a schematic cross sectional view of a bonded structure 2according to an embodiment. The bonded structure 2 can comprise a firstelement 22 (e.g., a first semiconductor device die) and a second element24 (e.g., a second semiconductor device die) stacked on and bonded tothe first element 22 along a bonding interface 26. Correspondingdielectric field regions (e.g., a first dielectric field region 28 and asecond dielectric field region 30) and corresponding contact pads (e.g.,first contact pads 16 and second contact pads 18) may be directly bondedwithout an intervening adhesive. The bonded structure 2 can include oneor more trace(s) 32 can provide a redundant electrical connection. Thus,in the event of a void or debris (fault 10) the traces 32 ensure thedesired connection between the elements 22, 24. Although not shown, itwill be understood that the contact pads 16, 18 each connect internallyto circuitry of their respective elements 22, 24, and that the tracesensure redundant connections of multiple pads to such internalcircuitry. The bonded structure 2 can include switching circuitry thatis connected to the trace(s) 32.

Beneficially, various embodiments disclosed herein can provide circuitry(e.g., switching circuitry) for electrical redundancy such that if afirst electrical connection between first and second elements fails, thefailed electrical connection can be rerouted or switched through aredundant electrical connection between the first and second elements.The disclosed embodiments can accordingly improve device yield byensuring that electrical connectivity between stacked dies remains evenwhen one or more interconnection between the elements has failed, e.g.,if a void or debris (fault 10) is disposed between contact pads of theelements.

Having the redundant pads close to one another risks both or all of theredundant pads being affected by the same bonding fault (e.g., void ordebris). Spacing redundant electrical interconnects relatively far apartmakes it more likely that if one connection is compromised by a bondingfault, a redundant pad can ensure the electrical connection to the otherdie is not lost. Embodiments disclosed herein can beneficially enablethe use of redundant pads at relatively large spacings withoutsignificant electrical losses. The use of active circuitry can enablehigh frequency operation at large distances with little electrical loss.

In various embodiments, the bonded structure can include first andsecond elements (e.g., first and second active integrated device dies)bonded to one another. Each element can comprise corresponding first andsecond pluralities of contact pads that can be electrically connected toone another to define a plurality of electrical connections along thebonding interface between the first and second elements. The connectionscan include contacts configured to carry relatively high frequencysignals (e.g., greater than about 50 Mhz, greater than about 100 MHz, orgreater than 200 MHz). In some embodiments, the connectivity ofelectrical connections between the first and second elements can betested to identify one or more failed electrical connections (forexample, connections in which a void, debris or other fault is disposedbetween opposing contact pads). In various embodiments, a boundary scanor built-in self-test (BIST) engine can be used to determineconnectivity. For example, the BIST engine can run a boundary scandiagnostic which identifies the faulty connections and verifies thatthere are functional alternate locations that can work beforeconnections are reassigned or rerouted. An e-fuse or other similarmechanisms, along with non-volatile look-up tables (LUTs) can logicallyreassign the electrical connections to redundant connections. Thereassignment or switching of connections can feed both sides of theconnections (at least two dies involved) so that the linkage andconnection is completed.

Thus, based upon available connectivity, a subset of spare pins orcontact pads to be reassigned to the broken interconnects can beidentified. The one or more failed electrical connections can bererouted or reassigned to one or more redundant electrical connectionson both sides of the bonding interface (e.g., on both dies) to completethe desired connection between the first and second elements. Thereroutings or reassignments can be implemented by switches ormultiplexers (MUXes) to re-route the nets. A longer distance can beenabled by reconditioning the signal with flops, redrivers, retimers,inverters, repeaters or similar structures disposed along the route orat the circuitry (e.g., at switching circuitry). By leveraging circuitrysuch as a switch or a multiplexer, the electrical load of the alternateelectrical paths should not consume power other than leakage power,which may occur from the repeaters (or other logic) used to carry thesignal to the alternate location.

The electrical connectivity of the plurality of electrical connectionscan be re-tested to verify connectivity of the one or more redundantelectrical connections. For example, in some embodiments, the boundaryscan can be re-run with the reassignments to validate the self-repair ofthe failed electrical connection. The embodiments disclosed herein canbe used in conjunction with directly bonded structures, as describedabove, but may also be used with other interconnections, such as copperpillars, solder balls, etc.

In FIG. 1C, the bonded structure 2 employs circuitry in each of firstand second elements 22, 24 to selectively re-route signals to alternateor redundant contact pads. As explained above, the first and secondelements 22, 24 can be bonded to one another along a bonding interface26. In the illustrated embodiment, the first and second elements 22, 24are directly bonded to one another without an adhesive. For example, asexplained above, corresponding first and second dielectric field regions28, 30 of the first and second elements 22, 24 may be directly bondedwithout an adhesive. Corresponding first and second pluralities ofcontact pads 16, 18 of the first and second elements 22, 24 may also bedirectly bonded to one another without an intervening adhesive. Forexample, the two bonded elements 22, 24 can be hybrid bonded such thatrespective dielectric regions 28, 30 are directly bonded without anadhesive and respective contact pads 16, 18 are directly bonded withoutan adhesive. In FIG. 1C, the first element 22 includes first and secondcontact pads 16 a, 16 b spaced apart from one another. In someembodiments, the first and second contact pads 16 a, 16 b can be spacedapart from one another by at least 10 microns, at least 50 microns, orat least 100 microns, for example, in a range of 10 microns to 5 mm, ina range of 10 mm to 1 mm, or in a range of 50 microns to 1500 microns.In some embodiments, the first and second contact pads 16 a, 16 b can bespaced apart by at least twice a pitch of the plurality of contact pads16, or at least 5 times the pitch. The second element 18 includes thirdand fourth contact pads 18 a, 18 b spaced apart from one another. Thethird and fourth pads 18 a, 18 b can be spaced apart by a spacingsimilar to that of the first and second pads 16 a, 16 b. The first andthird contact pads 16 a, 18 a can be disposed opposite one another andconfigured to electrically connect to one another. Similarly, the secondand fourth contact pads 16 b, 18 b can be disposed opposite one anotherand configured to electrically connect to one another. In otherembodiments, conductive adhesives may be used between correspondingcontact pads along the bonding interface.

FIGS. 2A-2B illustrate examples of circuitry 3, 4 comprising respectivebi-directional circuits, including tri-stated interconnections.Reference numerals used in conjunction with FIGS. 2A and 2B mayrepresent the same or generally similar components as those of FIG. 1C,unless otherwise noted. First transmit and receive flip-flops 36, 38 canbe provided in the first element 22. Second transmit and receiveflip-flops 40, 42 can be provided in the second element 24. The firstand second transmit flip-flops 36, 40 can comprise transmit transistors,and the first and second receive flip-flops 38, 42 can comprise receivetransistors. The flip-flops 36, 38, 40, 42 can each comprise asingle-transistor flip-flop and/or a multi-transistor flip-flop. Anoutput line 37 of the first transmit flip-flop 36 can be electricallyconnected at least partially through the trace 32 to an input line 39 ofthe first receive flip-flop 38 and to the second contact pad 16 b. Theinput line 39 of the first receive flip-flop 38 is connected to thefirst contact pad 16 a. An output line 41 of the second transmitflip-flop 40 can be electrically connected at least partially throughthe trace 32 to an input line 43 of the second receive flip-flop 42 andto the fourth contact pad 18 b. The input line 43 of the second receiveflip-flop 42 is connected to the third contact pad 18 a.

In various embodiments, if, for example, an electrical connectionbetween the second and fourth contact pads 16 b, 18 b is faulty, thesignal can be rerouted to a redundant electrical connection between thefirst and third contact pads 16 a, 18 a. Similarly, if an electricalconnection between the first and third contact pads 16 a, 18 a isfaulty, the signal can be rerouted to a redundant electrical connectionbetween the second and fourth contact pads 16 b, 18 b. Therefore, thecircuitry 3, 4 can have a first state in which an electrical signal istransferred between the first and third contact pads 16 a, 18 a and asecond state in which the electrical signal is transferred between thesecond and fourth contact pads 16 b, 18 b.

The circuitry 3, 4 can comprise a first tri-state driver 44 and a secondtri-state driver 46 that enable tri-stated interconnections. In someembodiments, the first tri-state driver 44 can be positioned between thefirst transmit flip-flop 36 and the trace 32 that connects the first andsecond contact pads 16 a, 16 b. In some embodiments, the secondtri-state driver 46 can be positioned between the second transmitflip-flop 40 and the trace 32 that connects the third and fourth contactpads 18 a, 18 b. The circuitry 4 can comprise a third tri-state driver48 and a fourth tri-state driver 50. As shown in FIG. 2B, in someembodiments, the third tri-state driver 48 can be positioned between thefirst receive flip-flop 36 and the trace 32 that connects the first andsecond contact pads 16 a, 16 b. In some embodiments, the fourthtri-state driver 50 can be positioned between the second receiveflip-flop 42 and the trace 32 that connects the third and fourth contactpads 18 a, 18 b.

FIGS. 2C-2D illustrate another example of circuitry 5, 6 that includes amultiplexer (MUX) 54 or demultiplexer (DEMUX) 52 in at least one of thefirst and second elements. Reference numerals used in conjunction withFIGS. 2C and 2D may represent the same or generally similar componentsas those of FIGS. 1C-2B, unless otherwise noted. FIG. 2C shows a DEMUXdevice. In FIG. 2D, a MUX device can be used. The circuitry 5, 6 caninclude a first and second transistors 53, 55. The circuitry 5 canconnect the second transistor 55 to an input of the DEMUX 52, and thecircuitry 6 can connect the second transistor 55 to an output of the MUX54. As shown in FIGS. 3A and 3B, the DEMUX 52 and/or MUX 54 in thesecond element 24 can be configured to select which of first and secondelectrical paths 56, 58 are to be used for a particular electricalsignal. One or more repeaters 60 can also be provided along the firstand second paths 56, 58. If it is determined that a first electricalconnection between first and third pads 16 a, 18 a is faulty, forexample, the DEMUX 52 and/or MUX 54 can switch to route the electricalsignal along the second path 58 to the redundant connection between thesecond and fourth pads 16 b, 18 b.

In the illustrated embodiments, the DEMUX 52 and the MUX 54 areconfigured to select between the first and second electrical paths 56,58, and a 1-to-2 demultiplexer and a 2-to-1 multiplexer are used as theDEMUX 52 and the MUX 54 respectively. However, in some embodiments, thecircuitry 5, 6 can be configured to select between more than twoelectrical paths and implement other types of DEMUX and MUX.

FIG. 3 illustrates another example of circuitry 7 that includes an ANDgate 62 in one or both of the first and second elements 22, 24.Reference numerals used in conjunction with FIG. 3 may represent thesame or generally similar components as those of FIGS. 1C-2D, unlessotherwise noted. Similar to the embodiment of FIGS. 2C and 2D, if bothinputs to the AND gate 62 indicate a good connection, then theelectrical signal can be transferred along the second path 58 to thesecond and fourth pads 16 b, 18 b (or the first path 56 to the first andthird pads 16 a, 18 a). If one of the inputs to the AND gate 62indicates a faulty connection (e.g., when the second and fourth pads 16b, 18 b have a faulty connection), then the electrical signal can betransferred along the first path 56 to the first and third pads 16 a, 18a. Although FIG. 3 illustrates an AND gate 62, it should be appreciatedthat other types of logic gates or active circuitry can be used toswitch between electrical pathways to the bonding interface.

FIG. 4 illustrates another example of circuitry 8 that includes a hashtopology including a plurality of multiplexers (MUX) 54 a, 54 b, 54 c,54 d, 54 e in the first and second elements 22, 24. Reference numeralsused in conjunction with FIG. 4 may represent the same or generallysimilar components as those of FIGS. 1C-3, unless otherwise noted. Thehash topology can enable the use of many-to-many interconnections, asopposed to one-to-one or many-to-one. As shown in FIG. 4, the firstflip-flop 53 can electrically connect to a plurality of multiplexers 54a, 54 b, 54 c, which can receive the electrical signal from the firstflip-flop 53. If the electrical connection along the bonding interface26 is faulty for one of the plurality of MUX 54 a, 54 b, 54 c, 54 d, 54e, then another of the MUX 54 a, 54 b, 54 c, 54 d, 54 e can transfer theelectrical signal to a corresponding contact pad at the bondinginterface 26. Also, one or a plurality of repeaters 60 can be providedalong the signal lines so as to boost or repeat the signal alongpossibly large distances, which can maintain high signal quality. Theuse of the hash topology can beneficially increase redundancy for thebonded structure, since each MUX 54 a, 54 b, 54 c, 54 d, 54 e canconnect to multiple flip-flops 53, 55, 63, 65 on a particular element.

For example, for each contact pad, accordingly, there may be more thanone redundant pad, which can share signal boosters, flops, retimers,drivers, inverters, etc. Thus, the many-to-many redundancy of FIG. 4enables every pin or contact pad to potentially access multipleredundant pads. For example, if there are 100 original pads or pins and10 redundant pads, then each of the 100 pins can access each of the 10redundant pads. This example can correct for 10 faults, but any suitablenumber of redundancies can be provided. For example, in someembodiments, a ratio of a first plurality of operational contact pads toa second plurality of redundant contact pads can be in a range of 2:1 to15:1, or in a range of 5:1 to 10:1.

The foregoing described actively connected redundant pads for signals.In some embodiments, each of the first and second elements 22, 24 cancomprise corresponding ground and power pads. Passively connectedredundant pads can be provided for the ground and power pads. Theredundant ground and power pads can be passively connected, for example,without active circuitry along the interconnecting path. Passivelyconnected redundant pads can be spaced apart from the correspondingfaulty power or ground pad by at least 10 microns, or at least 50microns. Passively connected redundant pads can be spaced apart from thecorresponding faulty power or ground pad by at least twice a pitch(e.g., twice a minimum pitch) of the contact pads.

Beneficially, the embodiments disclosed herein can provide electricalredundancy for connections across a bonding interface 26 between twobonded elements 22, 24. The disclosed embodiments can be used forsignals at relatively high frequencies, since active devices (such asrepeaters, flops, redrivers, retimers, inverters, etc.) can be providedto recondition the signal, even across relatively large distances. Thus,even for significantly increased point-to-point distances (for example,distances in a range of 0.3 mm to 1 mm, or greater than 1 mm) for agiven signal shunted to a redundant pad due to a faulty connection,signal strength at high frequencies can be maintained. In variousembodiments, the disclosed embodiments can be operated at frequencies of50 MHz or greater, 100 MHz or greater, or 200 MHz or greater.

The illustrated embodiments accordingly illustrates circuitry 3, 4, 5,6, 7, 8 that reroutes signal(s) from one contact pad to another,redundant contact pad. Although the illustrated embodiments show surfacepads with various or arbitrary types of internal, lateral connections,the concepts disclosed herein can be applicable to through substratevias (TSVs), whether the TSVs are internal to the element or passtherethrough. If the TSVs pass completely through a particular element,then the circuitry can provide for switching between outer dies of astack (e.g., with one or more intervening elements).

Thus, in one embodiment, a bonded structure is disclosed. The bondedstructure can include a first element having a first plurality ofcontact pads on a first surface, the first plurality of contact padsincluding a first contact pad and a second redundant contact pad spacedapart from one another along the first surface. The bonded structure caninclude a second element bonded to the first element. The second elementcan have a second plurality of contact pads on a second surface. Thesecond plurality of contact pads can include a third contact pad and afourth redundant contact pad spaced apart from one another along thesecond surface. The first contact pad can be disposed opposite to andconfigured to connect to the third contact pad. The second contact padcan be disposed opposite to and configured to connect to the fourthcontact pad. The bonded structure can include circuitry disposed in atleast the first element, the circuitry having a first state in which anelectrical signal is transferred to the first contact pad and a secondstate in which the electrical signal is transferred to the secondcontact pad.

In some embodiments, the bonded structure can include second circuitryin the second element, the second circuitry having a first state inwhich an electrical signal is transferred to the third contact pad and asecond state in which the electrical signal is transferred to the fourthcontact pad. The circuitry can form at least a portion of abidirectional tri-stated interconnect structure. The circuitry cancomprise a first receive flip-flop and a first transmit flip-flop, anoutput line of the first transmit flip-flop electrically connected to aninput line of the first receive flip-flop and to the second contact pad,the input line of the first receive flip-flop connected to the firstcontact pad. The second circuitry can comprise a second receiveflip-flop and a second transmit flip-flop, an output line of the secondtransmit flip-flop electrically connected to an input line of the secondreceive flip-flop and to the fourth contact pad, the input line of thefirst receive flip-flop connected to the third contact pad. Thecircuitry can comprise a multiplexer (MUX) or demultiplexer (DEMUX)electrically connected to a first flip-flop, and wherein the MUX orDEMUX is configured to selectively transfer the electrical signal to thefirst contact pad or the second contact pad. The bonded structure cancomprise a second flip-flop in the second element, the MUX or DEMUXconfigured to transfer the electrical signal to the second flip-flopalong a first path through the first contact pad or along a second paththrough the second contact pad. The circuitry can comprise an AND gateconfigured to selectively transfer the electrical signal to the firstcontact pad or the second contact pad. The circuitry can comprise afirst plurality of multiplexers (MUX) electrically connected to a firstflip-flop in the first element. A first MUX of the first plurality ofMUX can be configured to transfer the electrical signal to the firstcontact pad. The first MUX can be configured to receive the electricalsignal from the first flip-flop or a second electrical signal from asecond flip-flop in the first element. A second MUX of the firstplurality of MUX can be configured to receive the electrical signal fromthe first flip-flop and to transfer the electrical signal to the secondcontact pad. The second circuitry can comprise a second plurality ofmultiplexers (MUX) electrically connected to a second flip-flop. Thefirst plurality of contact pads can be directly bonded to the secondplurality of contact pads without an intervening adhesive. The bondedstructure can comprise first and second dielectric field regions on thefirst and second elements, the first and second dielectric field regionsdirectly bonded to one another without an adhesive. A void can bedisposed between at least a portion of the first and third contact pads,and wherein the second and fourth contact pads can be physically andelectrically contact one another. The first and third contact pads maynot be directly electrically connected to one another. The circuitry canbe in the second state. The first and second contact pads can be spacedapart by at least 50 microns. The first and second contact pads can bespaced apart by at least twice a pitch of the first plurality of contactpads.

In another embodiment, a method of providing electrical connectivityalong a bonding interface of a bonded structure including a firstelement bonded to a second element is disclosed. The method can includetesting electrical connectivity of a plurality of electrical connectionsbetween the first element and the second element to identify one or morefailed electrical connections. The method can include rerouting theidentified one or more failed electrical connections to one or moreredundant electrical connections between the first and second elements.

The method can include re-testing the electrical connectivity of theplurality of electrical connections to verify connectivity of the one ormore redundant electrical connections. The first element can be directlybonded to the second element without an intervening adhesive.

In another embodiment, a bonded structure is disclosed. The bondedstructure can include a first element having a first plurality ofoperational contact pads and a second plurality of redundant contactpads, wherein the first plurality of operational contact pads includesmore contact pads than the second plurality of redundant contact pads.The bonded structure can include a second element bonded to the firstelement. The second element can have a third plurality of operationalcontact pads and a fourth plurality of redundant contact pads. The firstplurality of operational contact pads can be disposed opposite to andconfigured to connect to the third plurality of operational contactpads. The second plurality of redundant contact pads can be disposedopposite to and configured to connect to the fourth plurality ofredundant contact pads. The bonded structure can include circuitrydisposed in at least the first element, the circuitry configured totransfer one or more electrical signals from a first number of pads fromthe first plurality of operational pads to a second number of pads fromthe second plurality of redundant pads, the first number greater thanthe second number.

In some embodiments, a ratio of the first plurality to the secondplurality and of the third plurality to the fourth plurality can be in arange of 2:1 to 15:1. The ratio of the first plurality to the secondplurality and of the third plurality to the fourth plurality can be in arange of 5:1 to 10:1. The first plurality of operational contact padscan comprise signal pads. Each of the first and second elements canfurther comprise corresponding ground and power pads. The bondedstructure can include passively connected redundant pads for the groundand power pads.

In another embodiment, a bonded structure is disclosed. The bondedstructure can include a first element having a first plurality ofthrough substrate vias (TSVs), the first plurality of TSVs including afirst TSV and a second redundant TSV spaced apart from one another. Thebonded structure can include a second element stacked on a first side ofthe first element, the second element having a plurality of contactpads. The plurality of contact pads can include a first contact pad anda second redundant contact spaced apart from one another. The first TSVcan be disposed opposite to and configured to connect to the firstcontact pad. The second TSV can be disposed opposite to and configuredto connect to the second contact pad. The bonded structure can includecircuitry disposed in at least the second element, the circuitryconnecting the first contact pad with the second contact pad, thecircuitry having a first state in which an electrical signal istransferred to the first TSV and a second state in which the electricalsignal is transferred to the second redundant TSV.

In some embodiments, the bonded structure can include a third elementstacked on a second side of the first element opposite to the firstside. The third element can have a second plurality of contact pads. Thesecond plurality of contact pads can include a third contact pad and afourth redundant contact pad spaced apart from one another. The thirdcontact pad can be disposed opposite to and configured to connect to thefirst TSV. The fourth contact pad can be disposed opposite to andconfigured to connect to the second TSV. The circuitry can be disposedin the first and/or third element. The first state can transfer theelectrical signal along the first contact pad, the first TSV and thethird contact pad. The second state can transfer the electrical signalalong the second contact pad, the second TSV and the fourth contact pad.One or more of the first through fourth contact pads can be connected toTSVs in the first and/or third elements.

All of these embodiments are intended to be within the scope of thisdisclosure. These and other embodiments will become readily apparent tothose skilled in the art from the following detailed description of theembodiments having reference to the attached figures, the claims notbeing limited to any particular embodiment(s) disclosed. Although thiscertain embodiments and examples have been disclosed herein, it will beunderstood by those skilled in the art that the disclosedimplementations extend beyond the specifically disclosed embodiments toother alternative embodiments and/or uses and obvious modifications andequivalents thereof. In addition, while several variations have beenshown and described in detail, other modifications will be readilyapparent to those of skill in the art based upon this disclosure. It isalso contemplated that various combinations or sub-combinations of thespecific features and aspects of the embodiments may be made and stillfall within the scope. It should be understood that various features andaspects of the disclosed embodiments can be combined with, orsubstituted for, one another in order to form varying modes of thedisclosed implementations. Thus, it is intended that the scope of thesubject matter herein disclosed should not be limited by the particulardisclosed embodiments described above, but should be determined only bya fair reading of the claims that follow.

1. A bonded structure comprising: a first element having a firstplurality of contact pads on a first surface, the first plurality ofcontact pads including a first contact pad and a second redundantcontact pad spaced apart from one another along the first surface; asecond element directly bonded to the first element without anintervening adhesive, the second element having a second plurality ofcontact pads on a second surface, the second plurality of contact padsincluding a third contact pad and a fourth redundant contact pad spacedapart from one another along the second surface, wherein the firstcontact pad is disposed opposite to and configured to connect to thethird contact pad, and wherein the second contact pad is disposedopposite to and configured to connect to the fourth contact pad; andcircuitry disposed in at least the first element, the circuitry having afirst state in which an electrical signal is transferred to the firstcontact pad and a second state in which the electrical signal istransferred to the second contact pad.
 2. The bonded structure of claim1, further comprising second circuitry in the second element, the secondcircuitry having a first state in which an electrical signal istransferred to the third contact pad and a second state in which theelectrical signal is transferred to the fourth contact pad.
 3. Thebonded structure of claim 2, wherein the circuitry forms at least aportion of a bidirectional tri-stated interconnect structure.
 4. Thebonded structure of claim 3, wherein the circuitry comprises a firstreceive flip-flop and a first transmit flip-flop, an output line of thefirst transmit flip-flop electrically connected to an input line of thefirst receive flip-flop and to the second contact pad, the input line ofthe first receive flip-flop connected to the first contact pad.
 5. Thebonded structure of claim 3, wherein the second circuitry comprises asecond receive flip-flop and a second transmit flip-flop, an output lineof the second transmit flip-flop electrically connected to an input lineof the second receive flip-flop and to the fourth contact pad, the inputline of the first receive flip-flop connected to the third contact pad.6. The bonded structure of claim 2, wherein the circuitry comprises amultiplexer (MUX) or demultiplexer (DEMUX) electrically connected to afirst flip-flop, and wherein the MUX or DEMUX is configured toselectively transfer the electrical signal to the first contact pad orthe second contact pad, and further comprising a second flip-flop in thesecond element, the MUX or DEMUX configured to transfer the electricalsignal to the second flip-flop along a first path through the firstcontact pad or along a second path through the second contact pad. 7.(canceled)
 8. The bonded structure of claim 2, wherein the circuitrycomprises an AND gate configured to selectively transfer the electricalsignal to the first contact pad or the second contact pad.
 9. The bondedstructure of claim 2, wherein the circuitry comprises a first pluralityof multiplexers (MUX) electrically connected to a first flip-flop in thefirst element, wherein a first MUX of the first plurality of MUX isconfigured to transfer the electrical signal to the first contact pad.10. (canceled)
 11. (canceled)
 12. (canceled)
 13. (canceled)
 14. Thebonded structure of claim 1, wherein the first plurality of contact padsis directly bonded to the second plurality of contact pads without anintervening adhesive.
 15. The bonded structure of claim 14, furthercomprising first and second dielectric field regions on the first andsecond elements, the first and second dielectric field regions directlybonded to one another without an adhesive.
 16. The bonded structure ofclaim 14, wherein a void is disposed between at least a portion of thefirst and third contact pads, and wherein the second and fourth contactpads physically and electrically contact one another.
 17. (canceled) 18.The bonded structure of claim 1, wherein the first and second contactpads are spaced apart by at least 50 microns or twice a pitch of thefirst plurality of contact pads.
 19. (canceled)
 20. (canceled) 21.(canceled)
 22. (canceled)
 23. A bonded structure comprising: a firstelement having a first plurality of operational contact pads and asecond plurality of redundant contact pads, wherein the first pluralityof operational contact pads includes more contact pads than the secondplurality of redundant contact pads; a second element directly bonded tothe first element without an intervening adhesive, the second elementhaving a third plurality of operational contact pads and a fourthplurality of redundant contact pads, wherein the first plurality ofoperational contact pads are disposed opposite to and configured toconnect to the third plurality of operational contact pads, and whereinthe second plurality of redundant contact pads are disposed opposite toand configured to connect to the fourth plurality of redundant contactpads; and circuitry disposed in at least the first element, thecircuitry configured to transfer one or more electrical signals from afirst number of pads from the first plurality of operational pads to asecond number of pads from the second plurality of redundant pads, thefirst number greater than the second number.
 24. The bonded structure ofclaim 22, wherein a ratio of the first plurality to the second pluralityand of the third plurality to the fourth plurality is in a range of 2:1to 15:1.
 25. (canceled)
 26. The bonded structure of claim 22, whereinthe first plurality of operational contact pads comprise signal pads.27. The bonded structure of claim 23, wherein each of the first andsecond elements further comprise corresponding ground and power pads.28. (canceled)
 29. A bonded structure comprising: a first element havinga first plurality of through substrate vias (TSVs), the first pluralityof TSVs including a first TSV and a second redundant TSV spaced apartfrom one another; a second element stacked on a first side of the firstelement, the second element having a plurality of contact pads, theplurality of contact pads including a first contact pad and a secondredundant contact spaced apart from one another, wherein the first TSVis disposed opposite to and configured to connect to the first contactpad, and wherein the second TSV is disposed opposite to and configuredto connect to the second contact pad; and circuitry disposed in at leastthe second element, the circuitry connecting the first contact pad withthe second contact pad, the circuitry having a first state in which anelectrical signal is transferred to the first TSV and a second state inwhich the electrical signal is transferred to the second redundant TSV.30. The bonded structure of claim 28, further comprising a third elementstacked on a second side of the first element opposite to the firstside, the third element having a second plurality of contact pads, thesecond plurality of contact pads including a third contact pad and afourth redundant contact pad spaced apart from one another, wherein thethird contact pad is disposed opposite to and configured to connect tothe first TSV, and wherein the fourth contact pad is disposed oppositeto and configured to connect to the second TSV.
 31. The bonded structureof claim 30, wherein the circuitry is disposed in the first and/or thirdelement; the first state transfers the electrical signal along the firstcontact pad, the first TSV and the third contact pad; and the secondstate transfers the electrical signal along the second contact pad, thesecond TSV and the fourth contact pad.
 32. (canceled)
 33. The bondedstructure of claim 31, wherein the first element is directly bonded tothe second element without an intervening adhesive.